The placement of prosthetic devices, such as stents and grafts, intraluminally and the conduct of operative procedures intraluminally has grown dramatically in recent years. In many of these placements and procedures, it is necessary to initially position a guidewire into a desired part of the lumen of a desired vessel or duct, such as a blood vessel. Once an initial guidewire is in place, a catheter or other tubular device may be positioned over the guidewire and used to convey another guidewire, a prosthesis, an endoscope or a surgical instrument into the desired blood vessel or duct.
There are a variety of techniques used to position guidewires in branching vessels intraluminally. One technique is to position a relatively stiff guidewire in a bodily vessel and then to pass over it a catheter having a region proximate its tip that normally assumes an angled, curved or some other configuration. On positioning the catheter over the stiff guidewire in the necessary position, the stiff guidewire is withdrawn allowing the region near the tip of the catheter to assume its normal configuration. A thin guidewire can then be fed through the catheter and directed in the direction assumed by the catheter. The thin guidewire is preferably sufficiently floppy that it is directed by the catheter in the direction assumed by the catheter rather than causing the catheter to adopt the configuration of the thin guidewire. As the first stiff guidewire must firstly be removed to allow the insertion of the thin guidewire, it is clinically undesirable to re-insert the stiff guidewire if required at a later time. Further, withdrawal of the stiff guidewire leads to there being no control over the position assumed by the catheter and it is common for the catheter to assume an undesirable position thereby requiring re-insertion of the stiff guidewire to correct the situation. The strength of the catheter further limits the stiffness of the thin guidewire or another secondary catheter that may be subsequently inserted through the catheter which can lead to further complications in successfully positioning a guidewire through the branching bodily vessel.
One example of a guiding catheter is described in U.S. Pat. No. 4,898,577 to Badger et al. The Badger guiding catheter comprises a single elongated shaft having a deflectable distal portion, the angle of deflection of the distal portion relative to the elongated shaft being controlled by a pull wire that extends from the distal portion back through a lumen to a proximal end of the catheter where it can be controlled by a physician. Once the distal portion is at the required deflection, the guidewire is fed through the catheter.
Another type of directable catheter is the so-called torquable catheter, an example of which is described in Australian Patent Specification AU-A-32951/95 to Lundquist. The Lundquist catheter once again has a single elongated shaft which has a flexible portion which can bend under the control of a physician to deflect the end of the catheter and so direct a guidewire passing therethrough in a desired direction.
Even with directable or torquable catheters, physicians still often encounter problems in achieving desired placement of guidewires and catheters in bodily vessels. Problems are especially encountered when it is necessary to direct a guidewire into a vessel branching of the main vessel. Conversely, problems also arise of a guidewire undesirably entering a branching vessel instead of remaining in the main vessel.
One example where it is often necessary to direct a guidewire into a branching vessel is in the placement of an intraluminal graft into a patient to achieve bridging and occlusion of an aneurysm of the aorta, iliac or other arteries. The present invention is directed to an alternative directional catheter which can be used for the intraluminal placement of a guidewire or catheter in a bodily vessel or cavity.